Human vision is rich in content and experience. We perceive contours, colors, contrast, brightness, shapes, textures, objects, relations, depth, and motion. Upon all this we construct meaning, we involuntarily or voluntarily focus or deflect attention, and we can be either conscious, or unconscious, of presented visual information. For content of which we are visually conscious, there is a qualitative or experiential aspect. It is like something for us to perceive the color blue, for example, and on this basis, we are said to be phenomenally conscious of the color blue, or of blueness.